Polycarbonate resin composition

ABSTRACT

To provide a polycarbonate resin composition excellent in low-birefringence and strength. 
     Disclosed is a polycarbonate resin composition prepared by blending
         a polycarbonate resin (A) prepared by forming carbonate bonds in a 95-5% by mole of dihydroxy compound represented by formula (1) and a 5-95% by mole of dihydroxy compound represented by formula (2) with a diester carbonate, and   a polycarbonate resin (B) prepared by forming carbonate bonds in dihydroxy compound represented by formula (3) with a diester carbonate or phosgene   in a 45-85% ratio by weight of (100×(A))/((A)+(B)).       

     
       
         
         
             
             
         
       
     
     (in the formula, R 1  and R 2  represent a hydrogen atom or methyl respectively.)

TECHNICAL FIELD

The present invention relates to a polycarbonate resin compositionprepared by blending a polycarbonate resin derived from a prescribedhydroxy compound and a polycarbonate resin derived from2,2-bis(4-hydroxyphenyl)propane, which is excellent in formability,strength and low-birefringence.

BACKGROUND ART

Polycarbonate resins formed of 2,2-bis(4-hydroxyphenyl)propane (popularname: bisphenol A) have been used in various optical materialapplications such as substrates of CD or DVD, optical films, opticalsheets, a wide variety of lenses, or prisms since they are excellent intransparency, heat resistance, low water-absorption properties, chemicalresistance, mechanical characteristics, and dimension stability.However, the resins formed of bisphenol A have large birefringence, andit is difficult to use them in the technical fields requiringlow-birefringence.

Therefore, in the technical fields requiring low-birefringence, acrylicresins, noncrystalline polyolefins, or polycarbonate resins having aspecific structure have been used. However, acrylic resins suffer fromhigh water-absorption properties, low dimension stability, or lowchemical resistance properties; and noncrystalline polyolefins sufferfrom low impact resistance, low chemical resistance properties or highprice. Furthermore, some of molded products formed of acrylic resins ornoncrystalline polyolefins don't exhibit sufficient low-birefringence,and therefore, in the technical field requiring lower-birefringence,such resins may not be used.

Examples of the polycarbonate resin having a specific structure includecopolymerization-polycarbonate resins derived from9,9-bis(3-methyl-4-hydroxyphenyl)fluorene andtricyclo[5.2.1.0^(2.6)]decanedimethanol (see Patent Document 1).Although injection-molded products formed of the resins are excellent inlow-birefringence, they suffer from low impact resistance strength.

Examples of the polycarbonate resin having a specific structure includealso copolymerization-polycarbonate resins derived from9,9-bis(4-(2-hydroxyethoxy)phenyl)fluorene and a prescribed hydroxycompound (see Patent Document 2); a polycarbonate resin compositioncontaining a copolymerization-polycarbonate resin derived from9,9-bis(4-(2-hydroxyethoxy)phenyl)fluorene and a prescribed hydroxycompound and a polycarbonate resin derived from bisphenol A in an amounthas been proposed (see Patent Document 3); and the applications thereofhave been also proposed (see Patent Document 4). Although thesepolycarbonate resins have lower birefringence compared with thepolycarbonate formed of bisphenol A, they suffer from low strength.

Therefore, low-birefringent polycarbonate resins excellent in strengthare required.

PRIOR ART DOCUMENTS Patent Documents

-   [Patent Document 1] JP-A-2000-169573-   [Patent Document 2 ] JP-A-2004-067990-   [Patent Document 3] JP-A-2004-359900-   [Patent Document 4] JP-A-2005-025149

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention

One object of the present invention is to solve the above-describedproblems, and to provide a transparent polycarbonate resin having highstrength and low birefringence.

Means of Solving the Problems

The present inventors conducted studies in order to solve theabove-described problems, and, as a result, found that the problemscould be solved by a polycarbonate resin composition prepared byblending

-   -   a polycarbonate resin (A) prepared by forming carbonate bonds in        a 95-5% by mole of dihydroxy compound represented by formula (1)        and a 5-95% by mole of dihydroxy compound represented by        formula (2) with a diester carbonate, and    -   a polycarbonate resin (B) prepared by forming carbonate bonds in        dihydroxy compound represented by formula (3) with a diester        carbonate or phosgene    -   in a 45-85% ratio by weight of (100×(A))/((A)+(B)); and then the        present invention was made.

(In the formula, R¹ and R² represent a hydrogen atom or methylrespectively.)

Effect of the Invention

According to the invention, it is possible to obtain a polycarbonateresin composition excellent in low-birefringence and strength. Thepolycarbonate resin composition is very useful since they can be usedvarious applications including not only transparent protective sheet ofa polarizing plate but also a wide variety of lenses, pickup lenses,prisms, optical sheets, optical films, light guide plates and the like.

MODE FOR CARRYING OUT THE INVENTION

The present invention relates to a polycarbonate resin compositionprepared by blending a prescribed polycarbonate (A) and a prescribedpolycarbonate (B) in a prescribed ratio.

The polycarbonate resin (A) is a polycarbonate resin which is preparedby forming carbonate bonds in a 95-5% by mole of dihydroxy compoundrepresented by formula (1) and a 5-95% by mole of dihydroxy compoundrepresented by formula (2) with a diester carbonate.

In the formula, R¹ and R² represent a hydrogen atom or methylrespectively.

Examples of the compound represented by formula (1) include9,9-bis(4-hydroxyphenyl)fluorene,9,9-bis(4-hydroxy-3-methylphenyl)fluorene,9,9-bis(4-hydroxy-3-ethylphenyl)fluorene and9,9-bis(4-hydroxy-2,6-dimethyl phenyl)fluorene. Among these,9,9-bis(4-hydroxy-3-methylphenyl)fluorene is preferably used.

The compound represented by formula (2) is concretely tricyclo[5.2.1.0^(2,6) decanedimethanol.

The dihydroxy compounds constituting the polycarbonate (A) are thedihydroxy compound represented by formula (1) and the dihydroxy compoundrepresented by formula (2). Regarding the ratios thereof, the ratio ofthe dihydroxy compound represented by formula (1) is from 5 to 95% bymole, and the ratio of the compound represented by formula (2) is from95 to 5% by mole. Preferably, the ratio of the dihydroxy compoundrepresented by formula (1) is from 10 to 70% by mole, and the ratio ofthe compound represented by formula (2) is from 90 to 30% by mole. Morepreferably, the ratio of the dihydroxy compound represented by formula(1) is from 15 to 60% by mole, and the ratio of the compound representedby formula (2) is from 85 to 40% by mole. Even more preferably, theratio of the dihydroxy compound represented by formula (1) is from 25 to45% by mole, and the ratio of the compound represented by formula (2) isfrom 75 to 55% by mole. The resin composition wherein the ratio of thecompound represented by formula (1) is less than 5% by mole may have alow glass transition point and lowered heat resistance, which is notpreferable. The resin composition wherein the ratio of the compoundrepresented by formula (1) is more than 95% by mole may have a highglass transition point and lowered flowability during molding, which isnot preferable.

The polycarbonate resin (A) may be prepared by polymerization of adihydroxy compound represented by formula (1) and a dihydroxy compoundrepresented by formula (2) in a presence of a diester carbonate andcatalyst according to any known melt-polycondensation method. Theproduction method will be described in detail later. The polycarbonateresin (A) may have a random, block or alternative copolymerizationstructure.

It is to be noted that the polycarbonate resin (A) contains only theunits derived from the hydroxy compound represented by formula (1), thehydroxy compound represented by formula (2) and a diester carbonate, andcontains essentially no unit derived from any monomer other than them.

The polycarbonate resin (B) is a polycarbonate resin prepared by formingcarbonate bonds in the dihydroxy compound represented by formula (3), or2,2-bis(4-hydroxyphenyl)propane (popular name: bisphenol A), with adiester carbonate or phosgene.

The polycarbonate resin (B) is preferably, but is not limited to, ahomopolymer formed of bisphenol A. Any bisphenol other than bisphenol Amay be copolymerized with a bisphenol A in a small amount so far as theproperties are not lowered.

The polycarbonate resin (B) may be prepared by polymerization of adihydroxy compound represented by formula (3) according to any knownmelt-polycondensation or phosgene method (interfacial polymerizationmethod). The production method will be described in detail later.

According to the invention, the blend ratio by weight of thepolycarbonate resins (A) and (B) (100×(A))/((A)+(B)) is from 45 to 85%by weight. Preferably, the ratio is from 50 to 80% by weight. The resincomposition wherein the blend ratio is less than 45% by weight may nothave low birefringence, which is not preferable. The resin compositionwherein the blend ratio is more than 85% by weight may have lowstrength, which is not preferable.

The polycarbonate resin composition of the invention may contain pluraltypes of the polycarbonate resins (A) and (B) respectively. In such acase, the values of (A) and (B) in the formula of (100×(A))/((A)+(B))mean the total weights of the plural types of the polycarbonate resins(A) and (B) respectively.

The polystyrene-converted weight average molecular weight (Mw) of thepolycarbonate resin (A) is from 20,000 to 300,000, or preferably from35,000 to 150,000. The blended resin composition containing thepolycarbonate resin (A) whose Mw is smaller than 20,000 may be brittle,which is not preferable. The polycarbonate resin composition containingthe polycarbonate resin (A) whose Mw is more than 300,000 has a highmelt viscosity, which may require undesirable severer conditions forbeing blended. Furthermore, such a resin composition may be subjected toan injection molding under severer conditions, which may causeundesirable silver patterns in the molded products.

The polystyrene-converted weight average molecular weight (Mw) of thepolycarbonate resin (B) is from 15,000 to 250,000, or preferably from20,000 to 110,000. The blended resin composition containing thepolycarbonate resin (B) whose Mw is smaller than 15,000 may be brittle,which is not preferable. The polycarbonate resin composition containingthe polycarbonate resin (B) whose Mw is more than 250,000 has a highmelt viscosity, which may require severer conditions for being blended.Furthermore, such a resin composition may be subjected to an injectionmolding under severer conditions, which may cause undesirable silverpatterns in the molded products.

The difference (ΔMw) of polystyrene-converted weight average molecularweight (Mw) between the polycarbonate resins (A) and (B) is preferablyfrom 0 to 120,000, or more preferably from 0 to 80,000. Thepolycarbonate resins (A) and (B), whose ΔMw is more than 12,000, mayshow a remarkably big difference in viscosity therebetween, and may becompatible hardly. Therefore, the resin composition, containing such thepolycarbonate resins, may show lowered transparency, which is notpreferable.

The polystyrene-converted weight average molecular weight (Mw) of theresin composition of the present invention prepared by blending thepolycarbonate resins (A) and (B) is preferably from 10,000 to 80,000, ormore preferably from 25,000 to 60,000. The resin composition having themolecular weight falling within the above-described scope may have goodformability, which is preferable.

The glass-transition temperature (Tg) of the polycarbonate resincomposition of the invention is preferably from 95 to 180 degreesCelsius, or more preferably from 105 to 170 degrees Celsius. Thecomposition, having Tg of lower than 95 degrees Celsius, may be used inonly a narrow temperature range, which is not preferable. Thecomposition, having Tg of higher than 180 degrees Celsius, may have tobe subjected to a molded process under severer conditions, which is notpreferable.

Next, examples of the method for preparing the polycarbonate resin (A)will be described in detail.

The polycarbonate resin (A) may be prepared by polymerization ofdihydroxy compounds represented by formulas (1) and (2) in a presence ofa diester carbonate and catalyst according to any knownmelt-polycondensation method.

As the diester carbonate, diphenyl carbonate, ditolyl carbonate,bis(chlorophenyl)carbonate, m-crezyl carbonate, dimethyl carbonate,diethyl carbonate, dibutyl carbonate, dicyclohexyl carbonate and thelike are exemplified. Among these, diphenyl carbonate is preferable. Thediester carbonate is preferably used by a ratio of from 0.98 to 1.20moles, or more preferably by a ratio of from 0.99 to 1.10 moles, withrespect to 1 mole of the total of the dihydroxy compounds.

As the basic-compound catalyst, alkali metal, alkali earth metalcompounds, nitrogen-containing compounds and the like are especiallyexemplified.

Specific examples thereof include organic acid salts, inorganic acidsalts, oxides, hydroxides, hydrides, and alkoxides of alkali metaland/or alkali earth metal compounds; and quaternary ammonium hydroxidesand the salts thereof, and amines. They may be used alone respectivelyor in combination thereof.

As the alkali metal compound, sodium hydroxide, potassium hydroxide,cesium hydroxide, lithium hydroxide, sodium hydrogen carbonate,potassium hydrogen carbonate, cesium hydrogen carbonate, lithiumhydrogen carbonate, sodium carbonate, potassium carbonate, cesiumcarbonate, lithium carbonate, sodium acetate, potassium acetate, cesiumacetate, lithium acetate, sodium stearate, potassium stearate, cesiumstearate, lithium stearate, sodium boron hydride, sodium boronphenylated, sodium benzoate, potassium benzoate, cesium benzoate,lithium benzoate, disodium hydrogen phosphate, dipotassium hydrogenphosphate, dilithium hydrogen phosphate, disodium phenylphosphate,disodium-, dipotassium-, dicesium- and dilithium-salts of bisphenol A,sodium-, potassium-, cesium- and lithium-salts of phenol, or the likeare used.

As the alkali earth metal compound, specifically, magnesium hydroxide,calcium hydroxide, strontium hydroxide, barium hydroxide, magnesiumhydrogen carbonate, calcium hydrogen carbonate, strontium hydrogencarbonate, barium hydrogen carbonate, magnesium carbonate, calciumcarbonate, strontium carbonate, barium carbonate, magnesium acetate,calcium acetate, strontium acetate, barium acetate, magnesium stearate,calcium stearate, calcium benzoate, magnesium phenylphosphate or thelike are used.

As the nitrogen-containing compound, specifically, quaternary ammoniumhydroxides having an alkyl or aryl group such as tetramethyl ammoniumhydroxide, tetraethyl ammonium hydroxide, tetrapropyl ammoniumhydroxide, tetrabutyl ammonium hydroxide and trimethylbenzyl ammoniumhydroxide, tertiary amines such as triethylamine, dimethylbenzylamineand triphenylamine, secondary amines such as diethylamine anddibutylamine, primary amines such as propylamino and butyl amine,imidazoles such as 2-methylimidazole and 2-phenylimidazole andbenzimidazole, bases and basic salts such as ammonia, tetramethylammonium borohydride, tetrabutyl ammonium borohydride, tetrabutylammonium tetraphenylborate, tetraphenyl ammonium tetraphenylborate, orthe like are used.

As the transesterification catalyst, salts of zinc, tin, zirconium orlead are preferably used, and may be used alone respectively or incombination thereof.

Specifically, zinc acetate, zinc benzoate, zinc 2-ethylhexanoate, thin(II) chloride, tin (IV) chloride, tin (II) acetate, tin (IV) acetate,dibutyltin dilaurate, dibutyltin oxide, dibutyltin dimethoxide,zirconium acetylacetonate, zirconium oxyacetate, zirconiumtetrabutoxide, lead (II) acetate, lead (IV) acetate or the like is used.

These catalysts may be respectively used preferably by a ratio of from10⁻⁹ to 10⁻³ mole, or more preferably by a ratio of from 10⁻⁷ to 10⁻⁴mole, with respect to 1 mole of the total dihydroxy compounds.

According to the invention, in a melt-polycondensation method, theabove-described raw materials and catalyst are used, and themelt-polycondensation is carried out by interesterification reactionthereof under heat and under an ordinary or reduced pressure while theby-products are removed. The reaction is usually carried out in two ormore multiple-stage step.

Specifically, the reaction in the first stage is carried out at atemperature of from 120 to 260 degrees Celsius, or preferably at atemperature of from 180 to 240 degrees Celsius, for from 0.1 to 5 hours,or preferably for from 0.5 to 3 hours. Next, the reaction of thedihydroxy compounds with a diester carbonate is continuously carried outwhile, for from 0.3 to 10 hours, the temperature is gradually raised toa final temperature of from 200 to 250 degrees Celsius and the pressureis gradually reduced to a final pressure of equal to or less than 1Torr. Such a reaction may be carried out in a continuous or batchmethod. The reaction device to be used may be any vertical type equippedwith an anchor agitating impeller maxblend agitating impeller, helicalribbon agitating impeller or the like, any horizontal type equipped witha paddle agitating impeller, grid agitating impeller, glass agitatingimpeller or the like, or any extruder type equipped with a screw. Andthey may be used in combination considering the viscosity of thepolymerized product

After the completion of the polymerization reaction, the catalyst isremoved or deactivated in order to maintain heat stability andhydrolysis stability of the polycarbonate resin thus obtained. Usually,a method for deactivating a catalyst by addition of known acid substanceis suitably applied. Preferable examples of the acid substance includeesters including butyl benzoate and dodencyl benzoate, aromatic sulfonicacids including p-toluene sulfonic acid and dodecylbenzene sulfonicacid, aromatic sulfonic acid esters including butyl p-toluene-sulfonate,hexyl p-toluenesulfonate, octyl p-toluenesulfonate, phenylp-toluenesulfonate and phenethyl p-toluenesulfonate, phosphoric acidsincluding phosphorous acid, phosphoric acid and phosphonic acid,phosphites including triphenyl phosphite, monophenyl phosphite, diphenylphosphite, monoethyl phosphite, diethyl phosphite, di-n-propylphosphite, di-n-butyl phosphite, mono-n-butyl phosphite, di-n-hexylphosphite, dioctyl phosphite and monooctyl phosphite, phosphatesincluding triphenyl phosphate, diphenyl phosphate, monophenyl phosphate,monoethyl phosphate, diethyl phosphate, monobutyl phosphate, dibutylphosphate, dioctyl phosphate and monoctyl phosphate, phosphonic acidsincluding diphenyl phosphonic acid, dioctyl phosphonic acid and dibutylphosphonic acid, phosphonates including diethyl phenyl phosphonate,phosphines including triphenyl phosphine andbis(diphenyl-phosphino)ethane, boric acids including boric acid andphenyl boric acid, aromatic sulfonic acid salts including dodecylbenzenesulfonic acid tetrabutyl phosphonium salt, organic halides includingbenzoyl chloride and p-toluene-sulfonyl chloride, alkyl sulfatesincluding dimethyl sulfate and organic halides including benzylchloride.

After the deactivation of the catalyst, a step to remove low boilingpoint compounds in the polymer with vaporization under a pressure of 0.1to 1 mmHg at a temperature of 200 to 350 degrees Celsius may be added.For its purpose, a horizontal apparatus equipped with a stirringimpeller with excellent surface renewing capacity such as paddleimpeller, lattice impeller, spectacle shaped impeller, etc. or thin filmvaporizer is suitably used.

Next, the method for preparing the polycarbonate resin (B) will bedescribed in detail.

One example of the method for preparing the polycarbonate resin (B) is amethod in which a dihydroxy compound and a diester carbonate aresubjected to a melt-polycondensation in a presence of a basic compoundcatalyst. This method is carried out almost based on the method ofproducing the polycarbonate resin (A). However, in the production methodof the polycarbonate resin (B), using no transition metal-typeinteresterification catalyst is preferable.

Another example of the method for preparing the polycarbonate resin (B)is a method in which a dihydroxy compound is subjected to an interfacialpolymerization with phosgene in a presence of solvent, an end-stoppingagent and an acid-binding agent. In the method, generally, the dihydroxycompound and the end-stopping agent are dissolved in an aqueous solutionof the acid-binding agent, and the reaction is carried out in a presenceof organic solvent.

As the acid-binding agent, for example, pyridine, or hydroxides ofalkali metal such as sodium hydroxide and potassium hydroxide arepreferably used. And as the solvent, for example, methylene chloride,chloroform, chlorobenzene, xylene or the like is preferably used.Furthermore, for promoting the polymerization, as a catalyst, tertiaryamines such as triethyl amine, or quaternary ammonium salts such astetra n-butyl ammonium bromide are used.

As the end-stopping agent which is used for adjusting the polymerizationdegree, mono-functional hydroxy compounds such as phenol,p-tert-butylphenol, p-cumylphenol and phenols having a long alkyl groupare used.

Furthermore, if desired, a small amount of an antioxidant such as sodiumsulfite and sodium hydrosulfite may be added.

The reaction is usually carried out at a temperature of from 0 to 150degrees Celsius, or preferably at a temperature of from 5 to 40 degreesCelsius. The reaction time depends on the reaction temperature, and, thereaction time is usually from 0.5 min. to 10 hours, or preferably from 1min. to 2 hours. And it is preferable that the pH value of the reactionsystem is kept equal to or more than 10 during the reaction

The method for producing the polycarbonate resin composition of theinvention is not limited, and it may be produced according to any one of

[1] a method in which solids of polycarbonate resins (A) and (B) areblended and then kneaded in a kneading machine;

[2] a method in which a solid of the polycarbonate resin (B) is added tothe polycarbonate resin (A) in a molten state and then kneaded;

[3] a method in which a solid of the polycarbonate resin (A) is added tothe polycarbonate resin (B) in a molten state and then kneaded; and

[4] a method in which polycarbonate resins (A) and (B) are blended in amolten state and then kneaded. Kneading may be performed in a continuousprocess or in a batch wise. When kneading is performed in a continuousprocess, an extruder is suitably applied. When kneading is performed ina batch wise, a labopastomill or a kneader is suitably applied. When anypolycarbonate resin produced by a melt-polycondensation process is used,it is preferable to perform kneading after deactivation of a catalyst interms of avoiding transesterfication during kneading. A catalystdeactivator may be kneaded together with the resins to be blend or maybe kneaded after blending. In such case, the range in which chemicalresistance of the resin composition is not impaired by random change dueto transesterification reaction should be maintained.

As another process for producing the polycarbonate resin composition ofthe present invention, also a process comprising dissolving thepolycarbonate resins (A) and (B) in a solvent and pouring it into a moldand then vaporizing the solvent may be applied. As the solvent,methylene chloride, chloroform and cresol are used. According to theprocess, it is possible to dissolve and add any additive at the sametime.

If necessary, antioxidant, a releasing agent, an ultraviolet absorber, aflowability improving agent, a reinforcing agent, crystalline nucleusagent, dye, an antistatic agent, and an antibacterial agent may be addedto the polycarbonate resin composition of the present invention. Theseadditives may be added to each the resins (A) and (B) or either onethereof prior to blending and kneading or may be added and kneaded atthe same time during blending and kneading or may be kneaded afterblending.

However, it is preferable that the polycarbonate resin composition ofthe invention substantially contains no polycarbonate resin other thanthe polycarbonate resins (A) and (B).

The polycarbonate resin composition of the present invention has lowbirefringence, and is very useful since they can be used variousapplications including not only transparent protective sheet of apolarizing plate but also a wide variety of lenses, pickup lenses,prisms, optical sheets, optical films, light guide plates and the like.Materials to be used for such an optical member are usually required tohave birefringence of not larger than 700 nm and to have bendingstrength of not smaller than 60 MPa in terms of processing suitabilityand durability. The polycarbonate resin composition of the presentinvention may satisfy these properties.

EXAMPLES

The present invention will be illustrated in further detail withreference to several examples below, which are not intended to limit thescope of the present invention. The evaluations of the obtainedpolycarbonate resin compositions were carried out according to thefollowing methods or the following apparatus.

-   1) Polystyrene-converted weight average molecular weight (Mw): Using    GPC, a standard curve was prepared with polystyrene standard samples    of which molecular weight (the distribution of molecular weight=1)    were known by using chloroform as a developing solvent. On the basis    of the standard curve, the value was calculated from the retention    times-   2) Glass transition temperature (Tg): Using a differential scanning    calorimeter (SSC-5200 manufactured by Seiko Instruments), DSC    measurements were carried out at the rate of 10 degrees Celsius/min.-   3) Bending elastic modulus: After the pellet of the polycarbonate    resin was dried at 120 degrees Celsius for 24 hours, the test piece    was prepared by subjecting the pellet to an injection forming with    an injection machine, “SG-150” manufactured by Sumitomo Heavy    Industries, Ltd., at a cylinder temperature of 255 degrees Celsius,    and was subjected to a measurement according to ASTM-D0790.-   4) Birefringent index: Birefringence (retardation) was measured    according to the following method.

4-1) Preparation of Cast Film

Each of the resins obtained according to the following examples wasdissolved in dichloromethane to give a solution having 5% by weightconcentration, and the solution was cast on a cast plate which wasconfirmed the horizontality. Dichloromethane was vaporized while thevaporizing amount was adjusted by occasionally covering the cast plate,and a resin film having a thickness of 100 micro meters was obtained.

4-2) Stretching of Film

The film was cut into a piece of 5 cm×5 cm, and was stretched at atemperature of higher than the glass transition temperature (Tg) by 10degrees Celsius at a stretching ratio of one and half times.

4-3) Measurement of Birefringence

Birefringence (retardation) of the obtained stretched film was measuredat a wavelength of 633 nm by using an ellipsometer, manufactured byk.k., Mizojiri Kogaku Kogyo.

Example 1

In a 50 L-reactor vessel equipped with an agitating instrument and adistillation apparatus, 8.14 kg (21.5 moles (33.6% by mole)) of9,9-bis(4-hydroxy-3-methylphenyl)fluorene, 8.32 g (42.4 moles (66.4% bymole)) of tricyclo[5.2.1.0^(2.6)]decanedimethanol, 13.81 g (64.5 moles)of diphenyl carbonate and 5×10⁻⁵ g (6×10⁻⁷ moles) of sodium hydrogencarbonate were placed, and heated to 215 degrees Celsius at 760 Torrunder a nitrogen gas-atmosphere for an hour under stirring.

After that, the pressure was reduced to 150 Torr for 15 minutes, andthen, the interesterification reaction was carried out at 215 degreesCelsius at 150 Torr for 20 minutes. Furthermore, the temperature wasraised to 240 degrees Celsius at 37.5 degrees Celsius/hr, and thenmaintained at 240 degrees Celsius for at 150 Torr 10 minutes. Afterthat, the pressure was reduced to 120 Torr for 10 minutes, and thenmaintained at 240 degrees Celsius at 120 Torr for 70 minutes. Afterthat, the pressure was reduced to 100 Torr for 10 minutes, and thenmaintained at 240 degrees Celsius at 100 Torr for 10 minutes. Thepressure was reduced to 1 Torr or less for 40 minutes, and then thepolymerization was carried out at 240 degrees Celsius at a pressure ofequal to or less than 1 Torr for 25 minutes under stirring. Aftertermination of the reaction, nitrogen gas was blown into the vessel forpressurizing, and then the produced polycarbonate resin was taken outwhile being subjected to pelletization. Polycarbonate resin having Mw of62300 and Tg of 142 degrees Celsius was obtained.

10.0 kg of the obtained polycarbonate was dried in vacuum at 100 degreesCelsius for 24 hours, added with diethyl phosphite in an amount of 10times by mole with respect to the amount of sodium hydrogen carbonate inthe resin, and glycerin monostearate in an amount of 300 ppm withrespect to the resin, mixed and kneaded with them by using an extruderat 260 degrees Celsius, and then pelletized. In this way, pellets (A)were obtained. The Mw of the pellet was 62,100.

8 kg of the obtained pellets and 2 kg of pellets of a polycarbonateresin formed of bisphenol A, “lupilon S-3000” (manufactured byMitsubishi Engineering-Plastics Corporation; Mw: 47800), weresufficiently mixed while being shaken, and were kneaded at 260 degreesCelsius in an extruder; and 6.8 kg of pelletized and blended pelletswere obtained. The pellets had Tg of 140 degrees Celsius, and anyinflection point was not found. From the result, that the blendedingredients were blended each other completely was confirmed. The Mwthereof was 58940. The bending strength and birefringence thereof weremeasured, and it was found that birefringence thereof was low, 250 nm,and that the bending strength thereof was high, 79 MPa.

Example 2

The steps were carried out in the same manner as Example 1, except that6 kg of the polycarbonate resin pellets (A) and 4 kg of pellets of apolycarbonate resin formed of bisphenol A, “lupilon S-3000”, wereblended and kneaded. The Mw thereof was 55600. The bending strength andbirefringence thereof were measured, and it was found that birefringencethereof was low, 440 nm, and that the bending strength thereof was high,83 MPa.

Example 3

The steps were carried out in the same manner as Example 1, except that5 kg of the polycarbonate resin pellets (A) and 5 kg of pellets of apolycarbonate resin formed of bisphenol A, “lupilon S-3000”, wereblended and kneaded. The Mw thereof was 54000. The bending strength andbirefringence thereof were measured, and it was found that birefringencethereof was low, 670 nm, and that the bending strength thereof was high,86 MPa.

Example 4

The polymerization was carried out in the same manner as Example 1,except that 6.05 kg (16.0 moles (25.0% by mole)) of9,9-bis(4-hydroxy-3-methylphenyl)fluorene, 9.41 kg (47.93 moles (75.0%by mole)) of tricyclo[5.2.1.0^(2.6)]decanedimethanol, 13.81 g (64.5moles) of diphenyl carbonate and 5×10⁻⁵ g (6×10⁻⁷ moles) of sodiumhydrogen carbonate were used, and polycarbonate resin pellets wereobtained. The Mw of the polycarbonate resin was 65300, and Tg thereofwas 116 degrees Celsius.

10.0 kg of the obtained polycarbonate was dried in vacuum at 100 degreesCelsius for 24 hours, added with diethyl phosphite in an amount of 10times by mole with respect to the amount of sodium hydrogen carbonate inthe resin, and glycerin monostearate in an amount of 300 ppm withrespect to the resin, mixed and kneaded with them by using an extruderat 260 degrees Celsius, and then pelletized. In this way, pellets (A)were obtained. The Mw of the pellet was 64,100.

5 kg of the obtained pellets and 5 kg of pellets of a polycarbonateresin formed of bisphenol A, “lupilon S-3000” (manufactured byMitsubishi Engineering-Plastics Corporation; Mw: 47800), weresufficiently mixed while being shaken, and were kneaded at 260 degreesCelsius in an extruder; and 6.8 kg of pelletized and blended pelletswere obtained. The pellets had Tg of 130 degrees Celsius, and anyinflection point was not found. From the result, that the blendedingredients were blended each other completely was confirmed. The Mwthereof was 52000. The bending strength and birefringence thereof weremeasured, and it was found that birefringence thereof was low, 680 nm,and that the bending strength thereof was high, 78 MPa.

Comparative Example 1

The polymerization was carried out in the same manner as Example 1. Theobtained resin was added with diethyl phosphite in an amount of 10 timesby mole with respect to the amount of sodium hydrogen carbonate in theresin, and glycerin monostearate in an amount of 300 ppm with respect tothe resin, and mixed and kneaded with them by using an extruder at 260degrees Celsius. The bending strength and birefringence of the obtainedpolycarbonate resin were measured, and it was found that birefringencethereof was very low, 1 nm, but the bending strength thereof was low, 11MPa.

Comparative Example 2

The steps were carried out in the same manner as Example 1, except that9 kg of the polycarbonate resin pellets (A) and 1 kg of pellets of apolycarbonate resin formed of bisphenol A, “lupilon S-3000”, wereblended and kneaded. The Mw thereof was 60600. The bending strength andbirefringence thereof were measured, and it was found that birefringencethereof was very low, 15 nm, but the bending strength thereof was low,15 MPa.

Comparative Example 3

The steps were carried out in the same manner as Example 1, except that6 kg of the polycarbonate resin pellets (A) and 4 kg of pellets of apolycarbonate resin formed of bisphenol A, “lupilon S-3000”, wereblended and kneaded. The Mw thereof was 52000. The bending strength andbirefringence thereof were measured, and it was found that the bendingstrength thereof was high, 90 MPa, but birefringence thereof was large,1010 nm.

TABLE 1 Polymer (A) Blend Bending (1)/(2) Ratio strength Birefringenceratio by mole (A)/(B) MPa nm Mw Example 1 33.6/66.4 80/20 79 250 58940Example 2 33.6/66.4 60/40 83 440 55600 Example 3 33.6/66.4 50/50 86 67054000 Example 4 25/75 50/50 78 680 52000 Comparative 33.6/66.4 100/0  111 62300 Example 1 Comparative 33.6/66.4 90/10 15 15 60600 Example 2Comparative 33.6/66.4 40/60 90 1010 52000 Example 3

REFERENTIAL EXAMPLE

The polymerization was carried out in the same manner as Example 1,except that 12.10 kg (32.0 moles (50.0% by mole)) of9,9-bis(4-hydroxy-3-methylphenyl)fluorene, 6.28 kg (32.0 moles (50.0% bymole)) of tricyclo[5.2.1.0^(2.6)]decanedimethanol, 13.81 g (64.5 moles)of diphenyl carbonate and 5×10⁻⁵ g (6×10⁻⁷ moles) of sodium hydrogencarbonate were used, and polycarbonate resin pellets were obtained. TheMw of the polycarbonate resin was 61300, and Tg thereof was 133 degreesCelsius.

10.0 kg of the obtained polycarbonate was dried in vacuum at 100 degreesCelsius for 24 hours, added with diethyl phosphite in an amount of 10times by mole with respect to the amount of sodium hydrogen carbonate inthe resin, and glycerin monostearate in an amount of 300 ppm withrespect to the resin, mixed and kneaded with them by using an extruderat 260 degrees Celsius, and then pelletized. In this way, pellets (A)were obtained. The Mw of the pellet was 60100.

5 kg of the obtained pellets and 5 kg of pellets of a polycarbonateresin formed of bisphenol A, “lupilon S-3000” (manufactured byMitsubishi Engineering-Plastics Corporation; Mw: 47800), weresufficiently mixed while being shaken, and were kneaded at 260 degreesCelsius in an extruder; and 6.8 kg of pelletized and blended pelletswere obtained. The pellets had Tg of 140 degrees Celsius, and anyinflection point was not found. From the result, that the blendedingredients were blended each other completely was confirmed.

The Mw thereof was 53000. The bending strength and birefringence thereofwere measured, and it was found that birefringence thereof was as small(680 nm) as those of Examples 1-4 but the bending strength thereof wasinferior (10 MPa) compared with Examples 1-4. Namely, it was found that,regarding the ratio by mole of the dihydroxy compound represented byformula (1) and the compound represented by formula (2) in thepolycarbonate resin A, the former was preferably 15-60% by mole and thelatter was preferably 85-40% by mole in terms of the bending strength.

1. A polycarbonate resin composition, obtained by blending apolycarbonate resin (A) and a polycarbonate resin (B), in a 45-85% ratioby weight of (100×(A))/((A)+(B)), wherein: the polycarbonate resin (A)is obtained by reacting 95-5% by mole of a dihydroxy compoundrepresented by formula (1):

wherein R¹ and R² individually represent a hydrogen atom or a methyl,and 5-95% by mole of a dihydroxy compound represented by formula (2):

with a diester carbonate to form carbonate bonds: and the polycarbonateresin (B) is obtained by reacting a dihydroxy compound represented byformula (3):

with the diester carbonate or phosgene to form carbonate bonds.
 2. Thepolycarbonate resin composition of claim 1, wherein R¹ in formula (1) isa hydrogen atom.
 3. The polycarbonate resin composition of claim 1,obtained by blending the polycarbonate resins (A) and (B) in a 50-80%ratio by weight of (100×(A))/((A)+(B)).
 4. The polycarbonate resincomposition of claim 1, wherein, in the polycarbonate resin (A), theratio by mole of the compound represented by formula (1) is from 15 to60%, and the ratio by mole of the compound represented by formula (2) isfrom 85 to 40%.
 5. The polycarbonate resin of claim 1, wherein thediester carbonate is diphenyl carbonate, ditolyl carbonate,bis(chlorophenyl)carbonate, m-crezyl carbonate, dimethyl carbonate,diethyl carbonate, dibutyl carbonate or dicyclohexyl carbonate.
 6. Thepolycarbonate resin composition of claim 1, wherein the diestercarbonate is diphenyl carbonate.
 7. The polycarbonate resin compositionof claim 1, wherein a polystyrene-converted weight average molecularweight (Mw) of the polycarbonate resin (A) is from 20,000 to 300,000,and a polystyrene-converted weight average molecular weight (Mw) of thepolycarbonate resin (B) is from 15,000 to 250,000.
 8. The polycarbonateresin composition of claim 1, wherein a difference, ΔMw, of thepolystyrene-converted weight average molecular weight (Mw) between thepolycarbonate resin (A) and the polycarbonate resin (B) is from 0 to120,000.
 9. The polycarbonate resin composition of claim 1, having aglass transition point from 95 to 180 degrees Celsius.